Arsenic is found naturally in ground water throughout various parts of the world and has long been an environmental concern because of its toxicity to a large spectrum of organisms, even at the parts-per-billion (ppb) level. A study presented in the Royal Geographic Society Arsenic Conference in 2007 reported that over 137 million people in more than 70 countries are affected by arsenic poisoning from drinking water. A large number of liver, lung, and kidney cancer cases as well as dermal conditions, such as hyperkeratosis and depigmentation, are connected to arsenic ingestion. Arsenic is second only to lead as the main inorganic contaminant in the original National Priority List (NPL) of Superfund sites. It is also one of the toxic materials regulated under the Resource Conservation and Recovery Act (RCRA). Therefore, the need exists for arsenic monitoring at Superfund sites, RCRA landfills, facilities handling arsenic-containing wastes, and sites. The US EPA estimated in 2001 that some 13 million people in the USA, mostly in the Western states, are exposed to arsenic in drinking water at >10 ppb level. According to an EPA report (EPA 815-R-02-003), there are approximately 54,000 community water systems, serving about 254 million people where groundwater is used as the source of drinking water supply in the US. The treatment plant process control systems in those areas need to be upgraded to monitor the level of arsenic well below 10 ppb to meet the new standards to protect citizens from receiving unsafe drinking water. The problem is more severe in developing countries. For example, in Bangladesh where 90% of citizens (130 million) use drinking water from shallow tube-wells, 200,000-270,000 deaths per year have been reported because of long-term ingestion of arsenic contaminated water. However, a reliable, quantitative and easy to use sensor for the determination of arsenic in drinking water, especially at low ppb levels, is not currently available. Conventional methods for the determination of arsenic, such as ICP-MS and ICP-AES, are labor-intensive, time consuming and expensive, while colorimetric tests are not quantitative. Most of the currently available colorimetric test kits use highly toxic chemicals containing mercury and also produce highly toxic gas arsine during the test. To address this need, Lynntech proposes to develop a disposable micro-cartridge based kit without any toxic metals like mercury or lead that can rapidly quantify arsenic in water using a simple battery operated colorimeter. This system will only require the user to pass an aliquot of water sample through a disposable cartridge and take a reading using a low cost handheld colorimeter. Additional merits include: detection of both oxidation states (III and V) of arsenic over a wide range (1-200 ppb), ease of handling, storage and transportation, long shelf life, low cost and manufacturability of the cartridges and associated reader.